The present invention relates to printing devices, such as typewriters or printers used in electrical data equipment, using a daisy wheel as a printing element, and more specifically to a printing device, in which a housing assembly includes a pair of housings relatively rockable around an axis, one of the housings carrying a keyboard thereon, and the other housing containing a printing mechanism therein.
In data input operation on the keyboard of the printing devices of this type, it is to be desired that an operator should be able to directly view data printed on a record medium on a platen. Such direct view can be hindered by a printing element, which travels along a print line, facing the platen. In these conventional printing devices, a daisy wheel, matrix-type print head and the like may be used as the print element. The devices are designed so that the direct data view is easy, even with use of a daisy wheel.
FIG. 1 shows one such prior art device using a daisy wheel. As shown in FIG. 1, a circular daisy wheel 4, rotated by a motor 3, is vertically mounted, substantially at right angles to the bottom surface of a housing 5, in order to facilitate the direct view of characters, printed on a printing sheet 2 on a platen 1. By doing this, types 4a on the wheel 4 can be located outside the operator's view. In this case, however, the wheel 4 has a considerable diameter, so that the height of the housing 5 of the device, which must be much greater than the diameter of the wheel 4, is substantial. Inevitably, therefore, the device is heavy and bulky to store or carry about.
In order to eliminate such a drawback, an improved printing device has been proposed and stated in Japanese Utility Model Disclosure No. 60-8072. In this device, the types 4a of the daisy wheel 4 are inclined at an angle to the bottom surface of the housing 5, so that the device is reduced in height, as shown in FIG. 2. In this case, however, characters, printed on the sheet 2, would be hidden behind the types 4a of the wheel 4 and a ribbon (not shown) between the types 4a and the sheet 2. In this arrangement, the printed characters can be seen only after shifting their position upward by turning the platen 1, and they must be returned to the original position for the printing of the next character. According to this method, however, the typing speed is lowered, due to a time lag, and the printing point may possibly be dislocated by the movement of the platen 1. If the device is provided with a liquid crystal display (LCD), the print can be checked, only indirectly, through the LCD. The use of the LCD would increase the cost of the device.
In the conventional printing devices, moreover, the keyboard gradually declines toward a typist or operator, for his easier view and operation of the keys. Naturally, therefore, the rear side of the housing must be made relatively high or thick. Thus, the housing is inevitably bulky and heavy, and cannot enjoy a compact design.
For the miniaturization of the printing devices, furthermore, there has been proposed an arrangement such that a housing assembly is formed of a pair of housings, which can rock relatively to each other. Printing devices of such an arrangement are stated in U.S. Pat. No. Des. 203,140 and Japanese patent disclosure No. 59-38822. In either of these devices, a keyboard is mounted on the one housing, while a printing mechanism is contained in the other housing. The two housings are coupled, for relatively rocking motion around an axis, by hinge-type pivot means. During use, the housings are stretched flat. When not in use, they can be bent over upon each other or closed, for compactness.
Neither of these printing devices can, however, settle those problems mentioned in connection with FIGS. 1 and 2.